I've come to the conclusion SquareSpace just isn't powerful enough to support a site like mine.
The fact is, I have items that have options. For example, I should be able to have a single product listing that lets you pick:
Manufacturer (10 options)
Model (10 options, should change dynamically when manufacturer is picked)
Color (11 options)
Clips (12 options)
Size (4 options)
So under SquareSpace, this would a product with a 10 x 11 x 12 x 4 variants, and that's not accounting for manufacturer as each manufacturer could I suppose have it's own product. That's literally 5,280 different variants, which of course is a bit past the 100 variant limit and way past the time it's worth inputting all that in.
It would be amazing to have options that simply apply to various product categories. For example, I want to sell shirts. Each shirt is going to have 11 color options and 4 size options. I shouldn't have to make 44 variants per shirt (I might have 90 shirts) for every shirt I want to sell. That's madness.
Anyway, my hope is someone in the future will come across this post and go elsewhere. This isn't a knock on SquareSpace necessarily, it's just SS is obviously designed for a very small shop, with a few items and only a few options per item.